The present invention is directed generally to caps for storage batteries, and more paticularly to a vented battery cap of two-piece snap-together construction which is less costly to manufacture and which provides improved dispersion of egressing battery gas.
Electrical storage batteries of the lead acid type typically comprise a plurality of individual cells each having a filler well through which electrolyte is replenished and through which hydrogen and oxygen gases generated within the cell during operation of the battery are egressed. Various types of vented caps, in both single form for covering a single filler well, and in ganged form for covering multiple filler wells, have been proposed for preventing the electrolyte from spilling or splashing out while allowing the gases developed within the battery to be vented. Such vented caps have relied on either tortuous vent paths, porous internal elements, or critically dimensioned vent apertures to minimize the possibility of the gas igniting and exploding within the battery.
Where critically dimensioned vent apertures have been relied upon, the vent apertures have typically been formed with a dimension to transverse to gas flow of less than approximately 0.007 inches, which corresponds to the minimum wall spacing required for flame propagation by a stoichiometric mixture of hydrogen and oxygen. Even with this critical vent dimensioning, it has been found necessary to also disperse the battery gas as it leaves the cap to prevent development of a persistent external flame at the vent aperture. Previously, this has been accomplished by providing a large number of individual vent apertures around the periphery of the cap, which undesirably complicated the structure of the caps and increased their cost of manufacture.
Typically, prior art vented battery caps, whether single or ganged in form, have been of two-piece construction, including a base member which fits down into the filler well of the battery, and a cover member which is bonded to the base member and cooperates therewith in forming a trap for electrolyte splashed from the battery and an escape path for gas egressing from the battery. The necessity of aligning and then bonding together the base and cover members undesirably added to the cost of manufacture of these prior art battery caps.
The present invention overcomes these shortcomings of prior art battery caps by providing a two-piece snap-together construction which is not only easier to assemble and therefore less costly to manufacture, but also provides improved dispersion for escaping battery gas and therefore improved protection against potentially damaging combustion. Such cost and performance improvements are particularly significant because of the high volume and highly competitive nature of the vented battery cap market.
Accordingly, it is a general object of the present invention to provide a new and improved vented cap for an electrical storage battery.
It is another object of the present invention to provide a new and improved vented battery cap which provides improved dispersion of egressing gases.
It is another object of the present invention to provide a new and improved vented battery cap which is less expensive to manufacture.
It is another object of the present invention to provide a vented battery cap of two-piece snap-together construction which provides improved dispersion of egressing battery gases.